1. Field of the Invention
The present invention relates to a reproducing apparatus, and more particularly, though not exclusively, to an apparatus for reproducing data from a disk recording medium.
2. Description of the Related Art
A high-density optical disks (e.g., a digital versatile disk (DVD) or a blu-ray disk) have been developed conventionally.
In a disk of this type, a groove is spirally formed thereon, and an optical beam is applied using this groove as a recording/reproducing track to write/read information. To superimpose addresses on the disk or to obtain a clock during reproduction, the groove is formed beforehand wobbling in a fixed cycle on the disk. When performing reproduction, an optical beam is applied to this wobbling track. From its reflected light, a clock associated with the wobbling cycle is generated, and address information is read. A clock, synchronized in phase with information contained in the reflected light, is generated to detect the information data (e.g., refer to Japanese Patent Application Laid-Open No. 2004-5926).
However, in the case of the apparatus discussed in Japanese Patent Application Laid-Open No. 2004-5926, the apparatus is equipped with two PLL circuits for generating the clock of the wobbling cycle where the clock is synchronized with the reproduced data. Thus, problems of increases in circuit size and costs have inevitably occurred.
Furthermore, unevenness in temperature characteristics, or processes between the two PLL circuits can cause a change in clock frequency, creating a problem in reliably obtaining a stable clock.